Method of making fluorinated phosphate esters



James C. Conly, Santa Monica, Calif assignor to Douglas Aircraft Company, Inc., Santa lylonic'a, Calif.

No Drawing. Application March 16, 1951,

Serial No. 216,091

8 Claims. (Cl. 260-461) This invention relates to a new method for preparing fluorina-ted alkyl esters of orthophosphoric acid and to the resulting new fluorinated phosphate esters as new chemical compounds, and relates more particularly to a commercially feasible or practicable process for the production of certain fluorinated phosphate esters and the resulting new chemical compounds of the general formula: (RO)3PO where R represents a fiuorinated alkyl radical having from 2 to carbon atoms and having a CR2 or CFa group, that is, having a fluorinated carbon atom with at least 2 fluorine atoms, bonded to the carbon atom connected to an oxygen of the phosphate radical and the i in 500 cc. of water.

carbon atom bonded to the oxygen of the phosphate radi- \l cal is bonded, in addition to the bond to this oxygen, only to atoms which are members of the group consisting of hydrogen and carbon; or a fluorinated alkoxyalkyl radical containing from 3 to 10 carbon atoms with at least 2 carbon atoms in the alkyl portion thereof and having a CR or CFa group, that is, having a fluorinated carbon atom with at least 2 fluorine atoms, bonded to the carbon atom connected to an oxygen of the phosphate radical and the carbon bonded to the oxygen of the phosphate radical is bonded, in addition to the bond to this oxygen, only to atoms which are members of the group consist ing of hydrogen and carbon. My invention more particularly relates to the production of such fluorinated-phosphate esters in which the substituents are fluorinated alky'l radicals. j

The compounds of this invention prepared by the novel process of this invention are generally nearly colorless liquids having mild pleasant odors. These esters have exceptional utility as flexibilizing plasticizers for fluorinated polymers, as non-flammable hydraulic fluids,.or as 4 stable liquid heat-transfer agents, in addition to many other uses based on their low viscosity at low temperatures, high stability and extraordinary fire resistance.

In general, in accordance with my invention, I react phosphorous oxychloride with an aqueoussolution offan alkali metal salt vof a fluorinated alkanol. or a fluorinated alkoxyalkanol, having in either case a fluorinated carbon atom with at least 2 fluorine atoms bonded to the carbinol carbon atom and the carbinol carbon atom, in addition to being bonded to oxygen, is bonded only to hydrogen 1 .2 a

or carbon atoms. Preferably the POC13 is added drop- Wise with stirring to the aqueous solution of the alkali metal alcoholate and the reaction preferably carried out at a temperature Within the range of 5 C. to +5 C., and in general it will be found advantageous to effect the reaction below about 10 C. The preferred alkali metal alcoholate is the sodium alcoholate, that is, the sodium salt of the fluorinated alkanol or the sodium salt of the fiuorinated alkoxyalkanol, although other alkali metal salts may be used, particularly including potassium. It is an especially important discovery in accordance with my invention that this method is effective and that new chemical compounds can be made with respect to such fluorinated alkanols or fluorinated alkoxyalkanols in which the carbinol carbon atom is bonded only to hydro- 2,754,317 Patented July 10, 1956 gen or carbon and to a fluorinated carbon atom having at least 2 fluorine atoms, that is, to a CF: or a CF3 group. This includes the primary, secondary and tertiary alcohols. The method in accordance with my invention has been found to be successful in giving good yields of good quality fluorinated phosphate esters.

My invention will 'be illustrated by the following example:

EXAMPLE Tris 2,2,3,3,4,4,4-heptafluorobutyl phosphate 51.2 grams of freshly distilled P0013 was cooled to 5 C. and added dropwise with good stirring to a solution of sodium 2,2,3,3,4,4,4-heptafluorobutyl alcohol at 5 C. made by mixing 44.4 grams of sodium hydroxide and 226 grams of the pure alcohol (boiling point 95-6 C.) The POCls was added at such a rate that the temperature at no time exceeded 5 C. and after addition was complete the mixture was stirred at 5 C. .for two hours. At the end of this time it was allowed to warm to room temperature and stirre d onehalf hour in addition. Then the heavy ester layer was separated from the water layer (which was washed with ethyl ether to remove any residual ester) and the oil layer washed with 2% NaOH, and subsequently with Water. It was then dried. The product was already of good purity, but was further purified by distilling (boiling point 70 C. at 0.7 mm.). This gave substantially pure tris 2,2,3,3,4,4,4-heptafluorobutyl phosphate.

The fluorinated alkanols which may be used in accordance with my invention may be represented by the following formula in which m is less than or equal to 2n+1 and n may gen 'or alkyl radicals. These particularly include those represented by' the following formulas:

CFs CHzOH CFs CF 2 CHzOH CFs (CF 2) 2CH2OH Y CFz (CF2) 3CH2OH CF3 (CF2 4CH2OH CF3 (CF2) 5CH2OH CFa (CF2) sCHzOH CFsCHOHCzHs CF; CHOHCsHz CF3CHOHC4H9 CF 3 CHOHCsHn CFs CHOHCsHrs CF3CHOHC7H15 CF 3 CHOHCsHrr CFs CF2CHOHC2H5 CF3CF2CHOHC3H7 I CFs CF2CHOHC4H9 CFsCFzCHOHCsHu CF 3 CF 2CHOHC6H13 CF3CF2CHOHC7H15 CF3CF2CHOHCBH1'7 CFs CF 2) 2CHOHC2H5 CFs (CFz ZCHOHC3H7 CFs CF 2) 2CHOHC4H9 CFs (CF2) 2CHOHC5H11 CFs (CFz 2CHOHCsH13 CFa CFz) 2CHOHC7H15 CF 3 CFz 2CHOHCsH1'z CF a (CH sCHOl-ICzHs CFs (CF2) sCHOHCzHv CFs (CF2)3CHOHC4H9 CF3(CF2)3CHOHC5H11 CF 3 CF2) 3CHOHC6H13 T-he fluorinated alcohols may be primary, secondary or tertiary. The fluorinated alkoxyalkanols particularly in- 'clude those represented by the following formulas:

The foregoing describes my invention in its preferred aspects, and illustrates my invention by way of specific embodiments and specific examples, but alterations and modifications may be made thereof without departing from the invention herein disclosed and claimed.

Having described my invention, I claim:

1. The method of making a tris fluorinated alkyl phosphate in which the fluorinated alkyl radicals are selected from the group consisting of a fluorinated alkyl radical having from 2 to 10 carbon atoms and having at least two fluorine atoms on acarbon atom bonded to the carbinol carbon atom andthe carbinol carbon atom in addition to being bonded to oxygen is bonded only to atoms which are members of the group consisting of hydrogen and carbon and a fluorinated alkoxyalkyl radical having at least two fluorine atoms on a carbon atom bonded to the carbinol carbon atom and the carbinol carbon atom in addition to being bonded to oxygen is bonded only to atoms which are members of the group consisting of atoms in the alkyl portion thereof, which comprises reacting phosphorous oxychloride with an aqueous solution of an alkali metal salt of a member of the group consisting of a fluorinated alkanol having at least two fluorine atoms on a carbon atom bonded to the carbinol carbon atom and the carbinol carbon atom in addition to being bonded to oxygen is bonded only to atoms which are members of the group consisting of hydrogen and carbon and a fluorinated alkoxyalkanol having at least two fluorine atoms on a carbon atom bonded to the carbinol carbon atom and the carbinol carbon atom in addition to being bonded to oxygen is bonded only to atoms which are members of the group consisting of hydrogen and carbon and having at'least two carbon atoms in the alkyl portion thereof.

2. The method as defined in claim 1 in which the alkali metal salt of a fluorinated alcohol is a sodium alcoholate.

3. The method of making a trifluoroalkyl phosphate which comprises reacting phosphorous oxychloride with an aqueous solution of an alkali metal salt of a fluorinated alcohol having from 2 to 10 carbon atoms and having at least two fluorine atoms on a carbon atom bonded to the carbinol carbon atom and the carbinol carbon atom in addition to being bonded to oxygen is bonded only to atoms which are members of the group consisting of hydrogen and carbon and thereby substituting fluoroalkoxy radicals for the chlorine of the phosphorous oxychloride.

4. The method as defined in claim 3 in which the alkali metal salt of the fluorinated alcohol is a sodium alcoholate. V

'5. The method as defined in claim 1 in which the reaction of phosphorous oxychloride with the alkali metal alcoholate is carried out at a temperature below 10 C.

6. The method as defined in claim 1 in which the reaction of phosphorous oxychloride with the alkali metal 'alcoholate is carried out at a temperature within the range of --'5 C. to +5 C.

7. The method as defined in claim 3 in which the reaction of phosphorous oxychloride with the alkali metal alcoholate is carried out at a temperature below 10 C.

8. The method as defined in claim 3 in which the reaction of phosphorous oxychloride with the alkali metal alcohola'te is carried out at a temperature within the range of -5 C. to +5 C.

References Cited in the file of this patent UNITED STATES PATENTS Benning July 10,1951

OTHER REFERENCES Swarts: Rec. Trav. Chim., vol. 28, pp. 166 to 170 (190. 7

Evans et al.: J. Chem. Soc., pp. 1310 to 1313 (1930). Groggins: Unit Processes in Organic Synthesis, 2d ed., pp. 564-5 (1938). e

Adler: Chemical Industries, vol. 51, p. 516 (1942).

hydrogen and carbon and having at least two carbon Nature, vol. 158, p. 384, Sept. 14, 1946. 

1. THE METHOD OF MAKING A TRIS FLUORINATED ALKYL PHOSPHATE IN WHICH THE FLUORINATED ALKYL RADICALS ARE SELECTED FROM THE GROUP CONSISTING OF A FLUORINATED ALKYL RADICAL HAVING FROM 2 TO 10 CARBON ATOMS AND HAVING AT LEAST TWO FLUORINE ATOMS ON A CARBON ATOM BONDED TO THE CARBINOL CARBON ATOM AND THE CARBINOL CARBON ATOM IN ADDITION TO BEING BONDED TO OXYGEN IS BONDED ONLY TO ATOMS WHICH ARE MEMBERS OF THE GROUP CONSISTING OF HYDROGEN AND CARBON AND A FLUORINATED ALKOXYALKYL RADICAL HAVING AT LEAST TWO FLUORINE ATOMS ON A CARBON ATOM BONDED TO THE CARBINOL CARBON ATOM AND THE CARBINOL CARBON ATOM IN ADDITION TO BEING BONDED TO OXYGEN IS BONDED ONLY TO ATOMS WHICH ARE MEMBERS OF THE GROUP CONSISTING OF HYDROGEN AND CARBON AND HAVING AT LEAST TWO CARBON ATOMS IN THE ALKYL PORTION THEREOF, WHICH COMPRISES REACTING PHOSPHOROUS OXYCHLORIDE WITH AN AQUEOUS SOLUTION OF AN ALKALI METAL SALT OF A MEMBER OF THE GROUP CONSISTING OF A FLUORINATED ALKANOL HAVING AT LEAST TWO FLUORINE ATOMS ON A CARBON ATOM BONDED TO THE CARBINOL CARBON ATOM AND THE CARBINOL CARBON ATOM IN ADDITION TO BEING BONDED TO OXYGEN IS BONDED ONLY TO ATOMS WHICH ARE MEMBERS OF THE GROUP CONSISTING OF HYDROGEN AND CARBON AND A FLUORINATED ALKOXYALKANOL HAVING AT LEAST TWO FLUORINE ATOMS ON A CARBON ATOM BONDED TO THE CARBINOL CARBON ATOM AND THE CARBINOL CARBON ATOM IN ADDITION TO BEING BONDED TO OXYGEN IS BONDED ONLY TO ATOMS WHICH ARE MEMBERS OF THE GROUP CONSISTING OF HYDROGEN AND CARBON AND HAVING AT LEAST TWO CARBON ATOMS IN THE ALKYL PORTION THEREOF. 